Next spring I'm going be rewiring my house. And for 'fun' I want to drop a
couple current sensors on the input side of the main panel.
Being a beginner 'nut', I'm looking for more accuracy then needed.
Voltage, Frequency, waveform will be taken care of later, but accurate
current has be a bit
There was a Circuit Cellar article on this many moons ago.
Basically, it was:
Take a torroid ferrite core, wrap ~20 turns of #20 through it, pass the wire
you want to sense current in through the core, and hook the output of the coil
to an op amp. Look at output of op amp with a/d converter.
Years ago I installed a TED-1000 (now obsolete) system from
http://www.theenergydetective.com/. Their software is terrible but
the system works. This system uses two current transformers and a
single voltage measurement system that all go inside your circuit
breaker box. I don't recall the
Getting 2 % is pretty easy, many commercial CT's at 0.3% at the
transformer, resistance of the wire from the CT to the load (burden in the
electrical world), and all the things that effect voltage measurements come
into play. A well designed setup can get to 0.5%.
Thanks to surplus a classic 5A
